CN101965088A - Discharge lamp lighting device, projector, and driving method of discharge lamp - Google Patents

Abstract

The present invention provides a discharge lamp lighting device, a control method thereof and a projector which suppresses the formation of constant convection in a discharge lamp and prevents unbalanced consumption of electrodes and unbalanced precipitation of electrode materials. Alternately execute the first DC drive process and the first AC drive process in the first interval, alternately execute the second DC drive process and the second AC drive process in the second interval different from the first interval, and execute the second DC drive process alternately in the first DC drive process In the process, the control of supplying the first direct current is implemented, and in the first AC drive process, the control of supplying the first AC current that repeats the first polarity component and the second polarity component is implemented, and in the second DC drive process, the control of supplying The control of the 2nd direct current, in the 2nd alternating current driving process, implement the control of supplying the 2nd alternating current of repeating the 1st polarity component and the 2nd polarity component, make the period of executing the 1st direct current driving process and execute the 2nd direct current The length of at least one of the driving processing periods changes with time.

Description

Discharge lamp lighting device, projector, and driving method of discharge lamp

technical field

The present invention relates to a discharge lamp lighting device, a projector, a method for driving a discharge lamp, and the like.

Background technique

As a light source of a projector, a discharge lamp (discharge lamp) such as a high-pressure mercury lamp or a metal halide lamp is generally used. In these discharge lamps, the shape of the electrodes changes because the meltability decreases due to wear of the electrodes due to the discharge and/or the progress of crystallization of the electrodes accompanying the lapse of the accumulated lighting time. In addition, when a plurality of protrusions grow on the tip of the electrode and irregular consumption of the electrode main body progresses along with this, the starting point of the arc moves and/or the length of the arc changes. These phenomena are undesirable because they lead to a reduction in the luminance of the discharge lamp and shorten the life of the discharge lamp.

As a method for solving this problem, a discharge lamp lighting device (Patent Document 1) that drives a discharge lamp using alternating currents with different frequencies is known. Also, a discharge lamp lighting device (Patent Document 2) that supplies a drive current obtained by intermittently inserting a DC into a high-frequency AC to a discharge lamp is known.

Patent Document 1: JP-A-2006-59790

Patent Document 2: Japanese Unexamined Patent Publication No. 1-112698

However, even if the discharge lamp is driven only with alternating currents of different frequencies as in Patent Document 1, or only a drive current obtained by intermittently inserting DC into high-frequency AC is supplied to the discharge lamp as in Patent Document 2, , it is still possible to form a constant convection with luminescence in the discharge lamp, unbalanced consumption of electrodes and/or unbalanced precipitation of electrode materials, and/or possible blackening, which occurs due to excessive evaporation of electrode materials It is caused by the adhesion of electrode material on the inner wall of the seal.

Contents of the invention

The present invention has been made in view of the above problems. According to several aspects of the present invention, it is possible to provide a discharge lamp lighting device, a control method for a discharge lamp lighting device, and a projector, which can suppress the formation of constant convection in the discharge lamp and prevent unbalanced consumption of electrodes and unbalanced precipitation of electrode materials. , Inhibit the excessive melting of the electrode tip, prevent the blackening of the electrode material attached to the inner wall of the seal, and keep the protrusion of the electrode tip well.

A discharge lamp lighting device according to one aspect of the present invention includes: a discharge lamp driving unit that supplies a driving current to the discharge lamp to drive the discharge lamp; and a control unit that controls the discharge lamp driving unit; Alternately execute the first DC drive process and the first AC drive process in the first interval, and alternately execute the second DC drive process and the second AC drive process in the second interval different from the above-mentioned first interval. In the above-mentioned first DC drive process, In the above-mentioned first alternating-current drive process, the control of the first direct current supply starting from the first polarity and consisting of the first polarity component is carried out as the above-mentioned driving current supply, and the control of repeating the first polarity component and the first polarity component as the above-mentioned driving current supply is carried out. In the control of the first alternating current of the second polarity component, in the above-mentioned second direct current driving process, the control of supplying the second direct current starting from the second polarity and consisting of the second polarity component as the driving current is carried out, In the above-mentioned 2nd AC drive process, implement the control of supplying the 2nd AC current which repeats the 1st polarity component and the 2nd polarity component as the above-mentioned drive current, so that the period during which the above-mentioned 1st DC drive process is performed and the period during which the above-mentioned 2nd polarity component is executed The length of at least one of the periods of the DC drive process changes with time.

The first direct current may also consist of a plurality of current pulses of the first polarity component, and the second direct current may also consist of a plurality of current pulses of the second polarity component.

According to this discharge lamp lighting device, since the length of at least one of the period during which the first DC drive process is performed and the period during which the second DC drive process is performed is changed with time, a temperature difference can be generated between the two electrodes of the discharge lamp. (such as tens to hundreds of degrees), suppress the formation of constant convection in the discharge lamp, prevent the unbalanced consumption of the electrodes and the unbalanced precipitation of the electrode materials, suppress the excessive melting of the front end of the electrodes, and prevent the electrode materials from adhering to the inner wall of the seal. Blackened, and the protrusion of the electrode tip is well maintained.

In this discharge lamp lighting device, the control unit may change the length of at least one of the period during which the first DC drive process is executed and the period during which the second DC drive process is performed so as to repeatedly increase and decrease over time. .

According to this discharge lamp lighting device, since the length of at least one of the period during which the first DC drive process is performed and the period during which the second DC drive process is performed is repeatedly increased and decreased over time, it is possible to suppress the internal discharge of the discharge lamp. The formation of constant convection prevents unbalanced consumption of electrodes and unbalanced precipitation of electrode materials, inhibits excessive melting of the tip of the electrode, prevents blackening of the electrode material attached to the inner wall of the seal, and maintains the protrusion of the tip of the electrode well.

In this discharge lamp lighting device, the control unit may increase and decrease the length of at least one of the period during which the first DC drive process is performed and the period during which the second DC drive process is performed in a time-dependent manner. produce changes.

According to this discharge lamp lighting device, since the length of at least one of the period during which the first DC drive process is performed and the period during which the second DC drive process is performed is changed with time in a manner that increases and decreases repeatedly in stages, it is possible to further suppress The formation of constant convection in the discharge lamp prevents the unbalanced consumption of electrodes and the unbalanced precipitation of electrode materials, inhibits the excessive melting of the front end of the electrode, prevents the blackening of the electrode material attached to the inner wall of the seal, and keeps the front end of the electrode well. protrusion.

In this discharge lamp lighting device, the control unit may change the length of at least one of a period during which the first AC drive process is performed and a period during which the second AC drive process is performed with time.

According to this discharge lamp lighting device, since the length of at least one of the period during which the first AC drive process is executed and the period during which the second AC drive process is performed is varied with time, the formation of constant convection in the discharge lamp can be further suppressed, preventing Unbalanced consumption of electrodes and unbalanced precipitation of electrode materials suppresses excessive melting of the tip of the electrode, prevents blackening of the electrode material adhering to the inner wall of the seal, and maintains the protrusion of the tip of the electrode well.

A discharge lamp lighting device according to one aspect of the present invention includes: a discharge lamp driving unit that supplies a driving current to the discharge lamp to drive the discharge lamp; and a control unit that controls the discharge lamp driving unit; Alternately execute the first DC drive process and the first AC drive process in the first interval, and alternately execute the second DC drive process and the second AC drive process in the second interval different from the above-mentioned first interval. In the above-mentioned first DC drive process, In the above-mentioned first alternating-current drive process, the control of the first direct current supply starting from the first polarity and consisting of the first polarity component is carried out as the above-mentioned driving current supply, and the control of repeating the first polarity component and the first polarity component as the above-mentioned driving current supply is carried out. In the control of the first alternating current of the second polarity component, in the above-mentioned second direct current driving process, the control of supplying the second direct current starting from the second polarity and consisting of the second polarity component as the driving current is carried out, In the above-mentioned 2nd AC drive process, the control of supplying the 2nd AC current which repeats the 1st polarity component and the 2nd polarity component as the above-mentioned drive current is carried out, so that the period during which the above-mentioned 1st AC drive process is executed and the period during which the above-mentioned 2nd polarity component is executed The length of at least one of the periods of the AC drive process changes with time.

According to this discharge lamp lighting device, since the length of at least one of the period during which the first AC drive process is performed and the period during which the second AC drive process is performed is changed with time, the formation of constant convection in the discharge lamp can be suppressed, preventing electrode Unbalanced consumption and unbalanced precipitation of electrode materials suppress excessive melting of the electrode tip, prevent blackening of electrode material adhering to the inner wall of the seal, and maintain the protrusion of the electrode tip well.

In this discharge lamp lighting device, the control unit may change the length of at least one of the period during which the first AC drive process is executed and the period during which the second AC drive process is performed so as to repeatedly increase and decrease over time. .

According to this discharge lamp lighting device, since the length of at least one of the period during which the first AC drive process is performed and the period during which the second AC drive process is performed is changed with time in such a manner as to repeatedly increase and decrease, it is possible to suppress the internal discharge of the discharge lamp. The formation of constant convection prevents unbalanced consumption of electrodes and unbalanced precipitation of electrode materials, inhibits excessive melting of the tip of the electrode, prevents blackening of the electrode material attached to the inner wall of the seal, and maintains the protrusion of the tip of the electrode well.

In this discharge lamp lighting device, the control unit may increase and decrease the length of at least one of the period during which the first AC drive process is performed and the period during which the second AC drive process is performed in a time-dependent manner. produce changes.

According to this discharge lamp lighting device, since the length of at least one of the period during which the first AC drive process is performed and the period during which the second AC drive process is performed is changed with time in a manner that increases and decreases repeatedly in stages, it is possible to further suppress The formation of constant convection in the discharge lamp prevents the unbalanced consumption of electrodes and the unbalanced precipitation of electrode materials, inhibits the excessive melting of the front end of the electrode, prevents the blackening of the electrode material attached to the inner wall of the seal, and keeps the front end of the electrode well. protrusion.

A projector as one of the aspects of the present invention includes any of these discharge lamp lighting devices.

According to this projector, it is possible to further suppress the formation of constant convection in the discharge lamp, prevent unbalanced consumption of electrodes and unbalanced precipitation of electrode materials, suppress excessive melting of the tip of the electrodes, and prevent blackening of electrode materials attached to the inner wall of the seal. , and maintain the protrusion of the electrode tip well.

The driving method of the discharge lamp as one of the aspects of the present invention is used to light the discharge lamp by supplying a driving current, and is characterized in that the first DC driving step and the first AC driving step are alternately performed in the first interval, The second DC driving step and the second AC driving step are alternately performed in the second interval different from the first interval described above. The 1st direct current that the polarity component constitutes, in the above-mentioned 1st alternating-current drive step, supply the 1st alternating current that repeats the 1st polarity component and the 2nd polarity component as the above-mentioned drive current, in the above-mentioned 2nd direct-current drive step , as the above-mentioned driving current, supply a second direct current starting from the second polarity and consisting of the second polarity component, and in the above-mentioned second alternating current driving step, as the above-mentioned driving current supply, repeating the first polarity component and the second polarity The length of at least one of the period during which the first DC driving step is performed and the period during which the second DC driving step is performed varies with time.

According to the driving method of the discharge lamp, since the length of at least one of the period during which the first DC drive process is performed and the period during which the second DC drive process is performed is changed with time, a temperature difference can be generated between the two electrodes of the discharge lamp. (such as tens to hundreds of degrees), suppress the formation of constant convection in the discharge lamp, prevent the unbalanced consumption of the electrodes and the unbalanced precipitation of the electrode materials, suppress the excessive melting of the front end of the electrodes, and prevent the electrode materials from adhering to the inner wall of the seal. Blackened, and the protrusion of the electrode tip is well maintained.

The driving method of the discharge lamp as one of the aspects of the present invention is used to light the discharge lamp by supplying a driving current, and is characterized in that the first DC driving step and the first AC driving step are alternately performed in the first interval, The second DC driving step and the second AC driving step are alternately performed in the second interval different from the first interval described above. The 1st direct current that the polarity component constitutes, in the above-mentioned 1st alternating-current drive step, supply the 1st alternating current that repeats the 1st polarity component and the 2nd polarity component as the above-mentioned drive current, in the above-mentioned 2nd direct-current drive step , as the above-mentioned driving current, supply a second direct current starting from the second polarity and consisting of the second polarity component, and in the above-mentioned second alternating current driving step, as the above-mentioned driving current supply, repeating the first polarity component and the second polarity The length of at least one of the period during which the first AC drive step and the second AC drive step is performed varies with time.

According to the driving method of the discharge lamp, since the length of at least one of the period during which the first AC drive process is performed and the period during which the second AC drive process is performed is changed with time, the formation of constant convection in the discharge lamp can be suppressed, preventing Unbalanced consumption of electrodes and unbalanced precipitation of electrode materials suppresses excessive melting of the tip of the electrode, prevents blackening of the electrode material adhering to the inner wall of the seal, and maintains the protrusion of the tip of the electrode well.

Description of drawings

FIG. 1 is an explanatory view showing a projector as an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the configuration of a light source device.

FIG. 3 is an example of a circuit diagram of the discharge lamp lighting device according to the present embodiment.

FIG. 4 is a diagram for explaining the configuration of a control unit according to the present embodiment.

5(A) to 5(D) are explanatory diagrams showing the relationship between the polarity of the driving current supplied to the discharge lamp and the electrode temperature.

6(A) to 6(B) are diagrams for explaining the first section and the second section.

7(A) is a timing chart showing an example of the waveform of the driving current I in the first section, and FIG. 7(B) is a timing chart showing an example of the waveform of the driving current I in the second section.

Fig. 8 (A) is a chart showing the time-dependent change of the period during which the DC drive process is performed and the length of the period during which the AC drive process is performed, and Fig. 8 (B) is a graph showing the time-dependent change of the frequency and the number of cycles (times) The graph, FIG. 8(C) is a graph showing the time-dependent change of the anode period ratio.

Fig. 9 (A) is a graph showing the time-dependent change of the length of the period during which the DC drive process is performed and the length of the AC drive process, and Fig. 9 (B) is a graph showing the time-dependent change of the frequency and the number of cycles. 9(C) is a graph showing the time-dependent change of the anode period ratio.

Fig. 10 (A) is a graph showing the time-dependent change of the length of the period during which the DC drive process is performed and the length of the AC drive process, and Fig. 10 (B) is a graph showing the time-dependent change of the frequency and the number of cycles. 10(C) is a graph showing the time-dependent change of the anode period ratio.

FIG. 11 is a diagram illustrating an example of a circuit configuration of a projector according to the present embodiment.

Symbol Description

10 Discharge lamp lighting device, 20 Power control circuit, 21 Switching element, 22 Diode, 23 Coil, 24 Capacitor, 30 Polarity inverting circuit, 31-34 Switching element, 40 Control unit, 40-1 Current control mechanism, 40 -2 polarity inversion control mechanism, 41 system controller, 42 power control circuit controller, 43 polarity inversion circuit controller, 44 storage unit, 50 mirrors, 60 voltage detection unit, 61~63 resistor, 70 Lighting Circuit, 80 DC Power Supply, 90 Discharge Lamp, 91 Discharge Space, 92 First Electrode, 93 Second Electrode, 112 Main Reflector, 114 Fixing Part, 200 Light Source Device, 210 Light Source Assembly, 305 Parallelizing Lens, 310 Lighting Optical system, 320 color separation optical system, 330R, 330G, 330B liquid crystal light valve, 340 cross dichroic prism, 350 projection optical system, 500 projector, 502 image signal, 510 image signal conversion unit, 512R image signal (R), 512G image signal (G), 512B image signal (B), 520 DC power supply unit, 522 fixed part, 532 communication signal, 534 conductive part, 536 first terminal, 544 conductive part, 546 second terminal, 552p protrusion, 560G LCD panel (G), 560B LCD panel (B), 562p protrusion, 570 image processing device, 572R LCD panel (R) driving signal, 572G LCD panel (G) driving signal, 572B LCD panel (B) driving signal, 580CPU , 582 communication signals, 600 AC power supply, 700 screen

Detailed ways

Hereinafter, preferred embodiments of the present invention will be described in detail using the drawings. In addition, the embodiments described below are not intended to unduly limit the content of the present invention described in the claims. In addition, not all the configurations described below are essential configuration requirements of the present invention.

1. The optical system of the projector

FIG. 1 is an explanatory diagram showing a projector 500 as an embodiment of the present invention. Projector 500 has light source device 200 , parallelizing lens 305 , illumination optical system 310 , color separation optical system 320 , three liquid crystal light valves 330R, 330G, and 330B, cross dichroic prism 340 , and projection optical system 350 .

The light source device 200 has a light source module 210 and a discharge lamp lighting device 10 . The light source assembly 210 has a main reflector 112 , a sub reflector 50 and a discharge lamp 90 . The discharge lamp lighting device 10 supplies electric power to the discharge lamp 90 to light the discharge lamp 90 . The main reflector 112 reflects the light emitted from the discharge lamp 90 toward the irradiation direction D. As shown in FIG. The direction of illumination D is parallel to the optical axis AX. Light from the light source unit 210 passes through the collimating lens 305 and enters the illumination optical system 310 . The parallelizing lens 305 parallelizes the light from the light source assembly 210 .

The illumination optical system 310 equalizes the illuminance of the light from the light source device 200 in the liquid crystal light valves 330R, 330G, and 330B. In addition, the illumination optical system 310 adjusts the polarization direction of the light from the light source device 200 to one direction. The reason for this is to effectively use the light from the light source device 200 in the liquid crystal light valves 330R, 330G, and 330B. The light after adjusting the illuminance distribution and the polarization direction enters the color separation optical system 320 . The color separation optical system 320 separates incident light into three color lights of red (R), green (G), and blue (B). The three kinds of colored light are respectively modulated by liquid crystal light valves 330R, 330G, and 330B corresponding to the respective colors. The liquid crystal light valves 330R, 330G, and 330B include liquid crystal panels 560R, 560G, and 560B, and polarizing plates disposed on the light incident side and the light emitting side of the liquid crystal panels 560R, 560G, and 560B, respectively. The modulated three color lights are synthesized by the cross dichroic prism 340 . The synthesized light is incident on the projection optical system 350 . The projection optical system 350 projects incident light on a screen not shown. By this, an image is displayed on the screen.

In addition, as the configurations of the parallelizing lens 305 , the illumination optical system 310 , the color separation optical system 320 , the cross dichroic prism 340 , and the projection optical system 350 , various well-known configurations can be employed.

FIG. 2 is an explanatory diagram showing the configuration of the light source device 200 . The light source device 200 has a light source module 210 and a discharge lamp lighting device 10 . In the drawing, a cross-sectional view of a light source module 210 is shown. The light source assembly 210 has a main reflector 112 , a discharge lamp 90 and a sub-reflector 50 .

The shape of the discharge lamp 90 is a rod shape extending along the irradiation direction D from the first end portion 90e1 to the second end portion 90e2. The material of the discharge lamp 90 is, for example, a translucent material such as quartz glass. The central portion of the discharge lamp 90 bulges into a spherical shape, and a discharge space 91 is formed therein. In the discharge space 91, a gas serving as a discharge medium including a rare gas, a metal halide, and the like is enclosed.

In addition, in the discharge space 91 , two electrodes 92 and 93 protrude from the discharge lamp 90 . The first electrode 92 is arranged on the first end portion 90e1 side of the discharge space 91 , and the second electrode 93 is arranged on the second end portion 90e2 side of the discharge space 91 . The shape of these electrodes 92 and 93 is a rod shape extending along the optical axis AX. In the discharge space 91 , electrode front ends (also referred to as "discharge ends") of the respective electrodes 92, 93 are separated by a predetermined distance and face each other. In addition, the material of these electrodes 92 and 93 is metals, such as tungsten, for example.

A first terminal 536 is provided at a first end portion 90e1 of the discharge lamp 90 . The first terminal 536 and the first electrode 92 are electrically connected by the conductive member 534 passing through the inside of the discharge lamp 90 . Similarly, the second terminal 546 is provided at the second end portion 90e2 of the discharge lamp 90 . The second terminal 546 and the second electrode 93 are electrically connected by the conductive member 544 passing through the inside of the discharge lamp 90 . The material of each terminal 536, 546 is, for example, metal such as tungsten. Moreover, molybdenum foil can be utilized as each conductive member 534,544, for example.

These terminals 536 , 546 are connected to the discharge lamp lighting device 10 . The discharge lamp lighting device 10 supplies AC current to these terminals 536 and 546 . As a result, arc discharge occurs between the two electrodes 92 and 93 . The light (discharge light) generated by the arc discharge is radiated in all directions from the discharge position as indicated by the dotted arrow.

The main reflector 112 is fixed to the first end portion 90e1 of the discharge lamp 90 by the fixing member 114 . The shape of the reflection surface (the surface on the discharge lamp 90 side) of the main reflection mirror 112 is an elliptical shape of revolution. The main reflector 112 reflects the discharge light toward the irradiation direction D. As shown in FIG. In addition, the shape of the reflection surface of the main reflection mirror 112 is not limited to the shape of a spheroid, and various shapes that reflect the discharge light toward the irradiation direction D can be employed. For example, a parabolic shape of revolution may also be employed. In this case, the main reflector 112 can convert the discharge light into light substantially parallel to the optical axis AX. Thus, the parallelizing lens 305 can be omitted.

On the side of the second end portion 90e2 of the discharge lamp 90 , the sub-reflector 50 is fixed by the fixing member 522 . The shape of the reflecting surface (the surface on the discharge lamp 90 side) of the sub-reflector 50 is a spherical shape surrounding the second end portion 90e2 side of the discharge space 91 . The sub reflector 50 reflects the discharge light toward the main reflector 112 . Thereby, utilization efficiency of the light radiated from discharge space 91 can be improved.

In addition, as the material of the fixing member 114, 522, any heat-resistant material (for example, an inorganic adhesive) that can withstand heat generated by the discharge lamp 90 can be used. In addition, as a method of fixing the arrangement between the main reflector 112 and the sub-reflector 50 and the discharge lamp 90, it is not limited to the method of fixing the main reflector 112 and the sub-reflector 50 to the discharge lamp 90, and any method may be used. method. For example, the discharge lamp 90 and the main reflector 112 may be independently fixed to the casing of the projector (not shown). The same applies to the sub-mirror 50 .

2. The discharge lamp lighting device according to the first embodiment

(1) Configuration of the discharge lamp lighting device

FIG. 3 is an example of a circuit diagram of the discharge lamp lighting device according to the present embodiment.

The discharge lamp lighting device 10 includes a power control circuit 20 . The power control circuit 20 generates driving power to be supplied to the discharge lamp 90 . In the present embodiment, the power control circuit 20 includes a step-down chopper circuit that receives power from the DC power supply 80 as input, steps down the input voltage, and outputs a DC current Id.

The power control circuit 20 may include a switching element 21 , a diode 22 , a coil 23 and a capacitor 24 . The switching element 21 can be constituted by a transistor, for example. In the present embodiment, one end of the switching element 21 is connected to the positive voltage side of the DC power supply 80 , and the other end is connected to the cathode terminal of the diode 22 and one end of the coil 23 . Also, one end of a capacitor 24 is connected to the other end of the coil 23 , and the other end of the capacitor 24 is connected to the anode terminal of the diode 22 and the negative voltage side of the DC power supply 80 . A current control signal is input from the control unit 40 to the control terminal of the switching element 21 to control ON (conduction)/OFF (turn-off) of the switching element 21 . As the current control signal, for example, a PWM (Pulse Width Modulation, pulse width modulation) control signal may also be used.

Here, when the switching element 21 is turned on, a current flows through the coil 23 and energy is accumulated in the coil 23 . Then, when the switching element 21 is turned off, the energy accumulated in the coil 23 is released through the path of the capacitor 24 and the diode 22 . As a result, a DC current Id corresponding to the proportion of time during which the switching element 21 is turned on is generated.

The discharge lamp lighting device 10 includes a polarity inverting circuit 30 . The polarity inverting circuit 30 inputs the DC current Id output from the power control circuit 20, and by inverting the polarity at the given timing, generates and outputs a driving current I which lasts only for a controlled time. DC, or AC at any frequency. In this embodiment, the polarity inverting circuit 30 is constituted by an inverter bridge circuit (full bridge circuit).

The polarity inverting circuit 30 includes, for example, first to fourth switching elements 31 to 34 such as transistors, and the first and second switching elements 31 and 32 connected in series and the third and fourth switching elements connected in series The switching elements 33 and 34 are connected in parallel to each other and constituted. The control terminals of the first to fourth switching elements 31 to 34 are respectively input with polarity inversion control signals from the control unit 40 to control ON/OFF of the first to fourth switching elements 31 to 34. .

The polarity inverting circuit 30 alternately turns ON/OFF the first and fourth switching elements 31 and 34, and the second and third switching elements 32 and 33, so that the polarity of the DC current Id output from the power control circuit 20 Alternately reversed, from the common connection point of the first and second switching elements 31 and 32 and the common connection point of the third and fourth switching elements 33 and 34, a driving current I is generated and output, and the driving current I is only driven by DC for a controlled duration, or AC with arbitrary frequency.

That is, the control is such that when the first and fourth switching elements 31 and 34 are ON, the second and third switching elements 32 and 33 are turned OFF, and when the first and fourth switching elements 31 and 34 are OFF. The second and third switching elements 32 and 33 are turned ON. Accordingly, when the first and fourth switching elements 31 and 34 are turned ON, a drive current I flows from one end of the capacitor 24 in the order of the first switching element 31 , the discharge lamp 90 , and the fourth switching element 34 . Also, when the second and third switching elements 32 and 33 are turned ON, a driving current I flows from one end of the capacitor 24 in order of the third switching element 33 , the discharge lamp 90 , and the second switching element 32 .

In this embodiment, the power control circuit 20 and the polarity inverting circuit 30 are added together to correspond to a discharge lamp drive unit.

The discharge lamp lighting device 10 includes a control unit 40 . The control unit 40 controls the power control circuit 20 and the polarity inverting circuit 30 to control the holding time of the drive current I with the same polarity, the current value and frequency of the drive current I, and the like. The control unit 40 performs polarity inversion control on the polarity inversion timing of the polarity inversion circuit 30 by the drive current I, and the polarity inversion controls the holding time for the drive current I with the same polarity and the drive current I The frequency etc. are controlled. In addition, the control unit 40 performs current control on the power control circuit 20 , and this current control controls the current value of the output DC current Id.

The configuration of the control unit 40 is not particularly limited, but in the present embodiment, the control unit 40 includes a system controller 41 , a power control circuit controller 42 , and a polarity inverting circuit controller 43 . In addition, the control unit 40 may be partially or entirely constituted by a semiconductor integrated circuit.

The system controller 41 controls the power control circuit 20 and the polarity inversion circuit 30 by controlling the power control circuit controller 42 and the polarity inversion circuit controller 43 . The system controller 41 may also control the power control circuit controller 42 and the polarity inverting circuit to control device 43.

In the present embodiment, the system controller 41 includes a storage unit 44 . In addition, the storage unit 44 may be provided independently of the system controller 41 .

The system controller 41 may also control the power control circuit 20 and the polarity inversion circuit 30 based on the information stored in the storage unit 44 . In the storage unit 44 , for example, information related to driving parameters such as the holding time for which the driving current I continues with the same polarity, the current value, frequency, waveform, and modulation pattern of the driving current I may be stored.

The power control circuit controller 42 controls the power control circuit 20 by outputting a current control signal to the power control circuit 20 based on a control signal from the system controller 41 .

The polarity inversion circuit controller 43 controls the polarity inversion circuit 30 by outputting a polarity inversion control signal to the polarity inversion circuit 30 based on a control signal from the system controller 41 .

In addition, although the control unit 40 can also be realized by using a dedicated circuit to perform various controls of the above-mentioned control and the following processing, for example, it can also be executed by a CPU (Central Processing Unit, central processing unit) in the storage unit 44, etc. The stored control program functions as a computer to perform various controls of these processes. That is, as shown in FIG. 4 , the control unit 40 can also be configured as a current control mechanism 40-1 for controlling the power control circuit 20 and a polarity inversion control mechanism for controlling the polarity inversion circuit 30 through a control program. 40-2, to make a difference.

The discharge lamp lighting device 10 may include an operation detection unit. The operation detection part may also include the following voltage detection part 60 and/or current detection part. The voltage detection part 60, for example, detects the driving voltage V1a of the discharge lamp 90 and outputs the driving voltage information. The current detection part detects the driving current I and outputs the driving voltage V1a. current information. In this embodiment, the voltage detection unit 60 includes first and second resistors 61 and 62 .

In the present embodiment, the voltage detection unit detects the drive voltage V1a using a voltage divided by the first and second resistors 61 and 62 connected in parallel to the discharge lamp 90 and connected in series to each other. In addition, in the present embodiment, the current detection unit detects the drive current I using the voltage generated in the third resistor 63 connected in series to the discharge lamp 90 .

The discharge lamp lighting device 10 may also include a lighting circuit 70 . The lighting circuit 70 operates only when the lighting of the discharge lamp 90 starts, and when the lighting of the discharge lamp 90 starts, the insulation between the electrodes of the discharge lamp 90 is destroyed to form a high voltage required for a discharge path (similar to that of the discharge lamp). 90 is normally turned on) and is supplied between the electrodes of the discharge lamp 90 . In this embodiment, the lighting circuit 70 and the discharge lamp 90 are connected in parallel.

5(A) to 5(D) are explanatory diagrams showing the relationship between the polarity of the driving current supplied to the discharge lamp 90 and the electrode temperature. 5(A) and 5(B) show the working states of the two electrodes 92 and 93 . In the drawing, the tip portions of the two electrodes 92 and 93 are shown. Protrusions 552p, 562p are provided at the tips of the electrodes 92, 93, respectively. Discharge occurs between these protrusions 552p, 562p. In this embodiment, the movement of the discharge position (arc position) on each electrode 92, 93 can be suppressed compared to the case where there is no protrusion. However, such projections can also be omitted.

FIG. 5(A) shows the first polarity state P1 in which the first electrode 92 operates as an anode and the second electrode 93 operates as a cathode. In the first polarity state P1, electrons move from the second electrode 93 (cathode) to the first electrode 92 (anode) by discharge. Electrons are released from the cathode (second electrode 93). Electrons emitted from the cathode (second electrode 93 ) collide with the tip of the anode (first electrode 92 ). Heat is generated by this collision, and the temperature of the tip (protrusion 552p) of the anode (first electrode 92) rises.

FIG. 5(B) shows the second polarity state P2 in which the first electrode 92 operates as a cathode and the second electrode 93 operates as an anode. In the second polarity state P2 , opposite to the first polarity state P1 , electrons move from the first electrode 92 to the second electrode 93 . As a result, the temperature of the tip (protrusion 562p) of the second electrode 93 rises.

In this way, the temperature of the anode is easier to increase than that of the cathode. Here, the continuation of a state in which the temperature of one electrode is higher than that of the other electrode may cause various unfavorable conditions. For example, when the tip of a high-temperature electrode is excessively melted, undesired deformation of the electrode may occur. As a result, the arc length sometimes deviates from an appropriate value. In addition, the evaporated electrode material may adhere to the inner wall of the seal (the surface of the light-transmitting member surrounding the discharge space 91 ), causing blackening. On the other hand, when the melting of the tip of the low-temperature electrode is insufficient, the fine unevenness generated at the tip may remain without being melted. As a result, so-called arc jump (the arc moves in an unstable position) may occur.

As a technique for suppressing such disadvantages, it is possible to utilize alternating current driving in which the polarities of the electrodes are alternately repeated. FIG. 5(C) is a timing chart showing an example of the drive current I supplied to the discharge lamp 90 (FIG. 2). The horizontal axis represents the time T, and the vertical axis represents the current value of the driving current I. The drive current I represents the current flowing through the discharge lamp 90 . A positive value represents the first polarity state P1, and a negative value represents the second polarity state P2. In the example shown in FIG. 5(C), a rectangular wave alternating current is used. Furthermore, the first polarity state P1 and the second polarity state P2 alternately repeat. Here, the first polarity interval Tp represents the duration of the first polarity state P1, and the second polarity interval Tn represents the duration of the second polarity state P2. In addition, the average current value in the first polarity section Tp is Im1, and the average current value in the second polarity section Tn is -Im2. In addition, the frequency of the driving current I suitable for driving the discharge lamp 90 can be determined through experiments according to the characteristics of the discharge lamp 90 (for example, a value in the range of 30 Hz to 1 kHz is used). Other values Im1, -Im2, Tp, and Tn can also be determined by experiments in the same way.

FIG. 5(D) is a timing chart showing temperature changes of the first electrode 92 . The horizontal axis represents time T, and the vertical axis represents temperature H. In the first polarity state P1, the temperature H of the first electrode 92 increases, and in the second polarity state P2, the temperature H of the first electrode 92 decreases. In addition, since the first polarity state P1 and the second polarity state P2 are repeated, the temperature H periodically changes between the minimum value Hmin and the maximum value Hmax. In addition, although illustration is omitted, the temperature of the second electrode 93 changes in a phase opposite to that of the temperature H of the first electrode 92 . That is, in the first polarity state P1, the temperature of the second electrode 93 drops, and in the second polarity state P2, the temperature of the second electrode 93 rises.

In the first polarity state P1, since the tip of the first electrode 92 (protrusion 552p) is melted, the tip of the first electrode 92 (protrusion 552p) becomes smooth. Therefore, movement of the discharge position on the first electrode 92 can be suppressed. In addition, since the temperature of the tip of the second electrode 93 (protrusion 562p) is lowered, excessive melting of the second electrode 93 (protrusion 562p) is suppressed. Therefore, undesired deformation and blackening of electrodes can be suppressed. In the second polarity state P2, the environments where the first electrode 92 and the second electrode 93 are located are opposite. Therefore, by repeating the two states P1, P2, it is possible to suppress the failure of each of the two electrodes 92, 93.

Here, when the waveform of the current I is symmetrical, that is, when the waveform of the current I satisfies the conditions of "|Im1|=|-Im2|, Tp=Tn", between the two electrodes 92 and 93, The supplied power conditions are the same. Therefore, it can be inferred that the temperature difference between the two electrodes 92 and 93 becomes smaller. However, if the driving under such a symmetrical current waveform is continued, constant convection will occur in the discharge space 91, and the electrode material will be deposited or segregated locally on the electrode shaft and grown in a needle shape, and there will be a direction to surround the discharge space 91. Possibility of undesired discharges on walls of translucent material. Such undesired discharge causes deterioration of the inner wall and shortens the lifetime of the discharge lamp 90 . In addition, if the drive with such a symmetrical current waveform is continued, the electrode will maintain a constant temperature distribution for a long time, so the asymmetry of the electrode caused by the state change with the passage of time tends to develop further with time. .

In addition, if the electrode is overheated over a large area (the arc spot (hot spot on the electrode surface accompanied by arc discharge) increases), the shape of the electrode collapses due to excessive melting. In addition, the electrode material evaporates excessively, and the electrode material adheres to the inner wall of the seal, causing blackening to occur. On the contrary, if the electrode is too cold (the arc spot becomes smaller), the tip of the electrode cannot be melted sufficiently, and the tip of the electrode cannot be returned to a smooth state, that is, the tip of the electrode is easily deformed. Therefore, if the same energy supply state is continued to the electrode, the tip of the electrode (protrusions 552p, 562p) is likely to be deformed into an undesired shape.

(2) Control example of discharge lamp lighting device

Next, a specific example of control of the discharge lamp lighting device 10 according to the first embodiment will be described.

The control unit 40 of the discharge lamp lighting device 10 according to the first embodiment alternately executes the first DC drive process D1 (first DC drive step) and the first AC drive process A1 (first AC drive step) in the first section. ), alternately execute the second DC drive process D2 (second DC drive step) and the second AC drive process A2 (second AC drive step) in the second interval different from the first interval.

6(A) and 6(B) are diagrams for explaining the first section and the second section.

In the example shown in FIG. 6(A), the control unit 40 controls the discharge lamp driving unit in such a manner that the first section of the first DC drive process D1 and the first AC drive process A1 are alternately executed and alternately executed. The second section in which the second DC drive process D2 and the second AC drive process A2 are executed alternately appears.

In addition, in the example shown in FIG. 6(A), in the first interval, the first DC drive process D1 and the first AC drive process A1 are alternately executed in such a manner that the first DC drive process It starts with D1 and ends with the first AC drive process A1. Likewise, the second DC drive process D2 and the second AC drive process A2 are alternately executed in the second interval in such a manner that the second DC drive process D2 starts and the second AC drive process A2 ends.

In addition, the control part 40 may control the discharge lamp drive part so that the 3rd interval different from the 1st interval and the 2nd interval may appear. For example, in the example shown in FIG. 6(B), the control unit 40 controls the discharge lamp driving unit so that the third section in which the third AC drive process A3 is executed appears between the first section and the second section. .

In the first DC drive process D1, the control unit 40 implements control to supply a first DC current starting from the first polarity and consisting of the first polarity component as the drive current I, and in the first AC drive process A1, implements Control of a first alternating current that repeats a first polarity component and a second polarity component at a first frequency is supplied as a drive current I.

In the second DC drive process D2, the control unit 40 implements control to supply a second DC current starting from the second polarity and consisting of the second polarity component as the drive current I, and in the second AC drive process A2, implements Control of a second alternating current that repeats the first polarity component and the second polarity component at a second frequency is supplied as the driving current I.

Also, for example, in the example shown in FIG. 6(B), in the third AC drive process A3, the control unit 40 may also supply a third frequency different from the first frequency and the second frequency as the drive current I. The control of the third alternating current of the first polarity component and the second polarity component is repeated.

7(A) is a timing chart showing an example of the waveform of the driving current I in the first section, and FIG. 7(B) is a timing chart showing an example of the waveform of the driving current I in the second section. 7(A) and 7(B), the horizontal axis represents time, and the vertical axis represents the current value of the driving current I. In FIG. 7(A) and FIG. 7(B), the drive current I of the first polarity is set to be a positive value, and the drive current I of the second polarity is set to be a negative value.

In the example shown in FIG. 7(A), the control unit 40 performs a period from time t0 to time t1, a period from time t1 to time t2, a period from time t2 to time t3, and a period from time t2 to time t3. During the period from time t3 to time t4, the first DC drive process D1, the first AC drive process A1, the first DC drive process D1, and the first AC drive process A1 are respectively executed.

In the example shown in FIG. 7(A), the control unit 40 performs control to supply a driving current I in the first DC driving process D1, and the driving current I is 1/3 of the driving current I in the first AC driving process A1. The same polarity (1st polarity) is maintained for a time span of 2 cycles.

In addition, in the example shown in FIG. 7(A), the control unit 40 implements control to supply the driving current I in the first AC driving process A1, which is changed from the immediately preceding first DC driving process D1. Rectangular wave alternating current starting from the phase of the same polarity (1st polarity).

In the example shown in FIG. 7(B), the control unit 40 performs a period from time t5 to time t6, a period from time t6 to time t7, a period from time t7 to time t8, and a period from During the period from time t8 to time t9, the second DC drive process D2, the second AC drive process A2, the second DC drive process D2, and the second AC drive process A2 are respectively executed.

In the example shown in FIG. 7(B), the control unit 40 executes control to supply a drive current I in the second DC drive process D2 that is 1/3 of the drive current I in the second AC drive process A2. The same polarity (2nd polarity) is maintained for a period of 2 cycles.

In addition, in the example shown in FIG. 7(B), in the second AC drive process A2, as in the first AC drive process A1, the control unit 40 executes the control to supply the drive current I. The drive current I is equal to The first direct-current drive processes the rectangular-wave alternating current starting from the phase of the same polarity (first polarity) as D1.

Also, the period during which the discharge lamp 90 is driven under the same driving conditions is described as a step, the period during which the DC drive process is performed and the period during which the AC drive process is performed are described as a sequence, and the sequence included in one step The number is described as the number of cycles.

When the driving current I is DC, the current flows with the same polarity, so the arc spot becomes large, and the tip of the electrode can be melted into a smooth shape including unnecessary protrusions and the like. When the driving current I is alternating current, the current of the first polarity and the second polarity are alternately flowed, so the arc spot becomes smaller, and the growth of the protrusion at the tip of the electrode required as a discharge starting point can be promoted.

Therefore, by appropriately setting the driving conditions (the frequency during the period in which the driving current I is alternating current, the length of the period in which the driving current I is direct current and/or the length of the period in which it is alternating current, etc.), the driving current I is alternately repeated as a direct current. In this way, a good electrode shape can be maintained and the discharge lamp 90 can be stably lit.

However, if the discharge lamp 90 is continuously lit under the same driving conditions, constant convection accompanying light emission may be formed in the discharge lamp 90, resulting in unbalanced consumption of electrodes and/or unbalanced deposition of electrode materials.

Therefore, in the discharge lamp lighting device 10 according to the first embodiment, the control unit 40 changes the length of at least one of the period during which the first DC drive process D1 is performed and the period during which the second DC drive process D2 is performed with time. For example, the control unit 40 may change the length of at least one of the period during which the first DC drive process D1 and the period during which the second DC drive process D2 is performed so as to repeatedly increase and decrease over time. Thereby, a temperature difference (such as tens to hundreds of degrees) can be generated between the two electrodes of the discharge lamp 90, the formation of constant convection in the discharge lamp 90 can be suppressed, and unbalanced consumption of electrodes and unbalanced precipitation of electrode materials can be prevented.

In addition, the control unit 40 may change the length of at least one of the period during which the first DC drive process D1 is performed and the period during which the second DC drive process D2 is performed over time so as to repeatedly increase and decrease in stages.

Fig. 8 (A) is the graph that shows the time-dependent change of the period of performing DC drive process and the length of the period of performing AC drive process, and Fig. 8 (B) is a graph showing the change of frequency and number of cycles according to time, and 8(C) is a graph showing the time-dependent change of the ratio of the anode period. The horizontal axes all represent elapsed time. In addition, from time t11 to time t13 and from time t13 to time t14 are the first intervals, and from time t12 to time t13 are the second intervals.

In Fig. 8(A), the length of the period during which the DC drive process is performed is represented by the solid line A, the length of the period during which the first DC drive process D1 is performed is represented in the first interval, and the second DC drive process D1 is executed in the second interval. The length of the period of the drive process D2. In addition, in FIG. 8(A), the length of the period during which the AC drive process is executed is represented by a dotted line B, the length of the period during which the first AC drive process A1 is executed is represented in the first interval, and the second interval is represented in the second interval. The length of the period during which the AC drive processes A2.

In FIG. 8(B), the number of cycles is represented by a solid line C, the number of cycles for executing the first AC drive process A1 is represented in the first interval, and the number of cycles for executing the second AC drive process A2 is represented in the second interval. In addition, in Fig. 8 (B), represent frequency with dotted line D, represent the 1st frequency in the 1st AC drive process A1 in the 1st interval, represent the 2nd frequency in the 2nd AC drive process A2 in the 2nd interval. frequency.

In FIG. 8(C), the ratio of the anode period represents the ratio of the time during which the first electrode 92 is an anode in one step period. In addition, when the ratio of the time when the 1st electrode 92 is an anode and the ratio of the time when the 2nd electrode 93 is an anode are totaled, it becomes 1. That is, the relationship between the anode ratio of the first electrode 92 and the anode ratio of the second electrode 93 is expressed by the following formula (1).

The anode ratio of the second electrode 93=1-the anode ratio of the first electrode 92...(1)

In the example shown in FIG. 8(A), one step is set to one second, and the control unit 40 performs control to gradually reduce the length of the period for executing the first DC drive process D1 from time t11 to time t12. . The control unit 40 performs control such that the length of the period during which the second DC drive process D2 is executed increases in steps and then decreases in steps from time t12 to time t13. The control unit 40 performs control to increase the length of the period during which the first DC drive process D1 is executed in stages from time t13 to time t14.

In addition, in the example shown in FIG. 8(A), the length of the period during which the first AC drive process A1 and the second AC drive process A2 are executed is constant. Therefore, in order to make the length of one step constant, as shown in FIG. 8(B), the number of cycles is changed according to the length of the period during which the first DC drive process D1 and the second DC drive process D2 are executed. In addition, in the example shown in FIG. 8(B), the first frequency in the first AC drive process A1 and the second frequency in the second AC drive process A2 are all constant values of the same value.

As shown in FIGS. 8(A) and 8(B), when the driving conditions are changed over time, the anode ratio of the first electrode 92 changes over time as shown in FIG. 8(C). The larger the anode ratio, the higher the electrode temperature becomes, and the smaller the anode ratio, the lower the electrode temperature becomes. Therefore, FIG. 8(C) means that the temperature of the first electrode 92 changes with time. In addition, the anode ratio of the second electrode 93 is expressed by the formula (1), and changes in the opposite direction to the anode ratio of the first electrode 93 . Therefore, FIG. 8(C) means that the temperature of the second electrode 93 also changes with time.

In addition, in the above-mentioned example, although the example in which the lengths of both the period during which the first DC drive process D1 is performed and the period during which the second DC drive process D2 is performed is changed over time in a manner of repeatedly increasing and decreasing in stages, However, for example, when the thermal conditions of the first electrode 92 and the second electrode 93 of the discharge lamp 90 are greatly different (ease of temperature rise of the electrodes, etc.), the period during which the first DC drive process D1 is performed may be set as follows: And one of the lengths of the period during which the second DC drive process D2 is executed is changed so that the anode ratio of the electrode side where the temperature becomes higher is lower than the anode ratio of the other electrode.

Like the example shown in FIG. 8(A) to FIG. 8(C), it can be considered that the length of at least one of the period during which the first DC drive process D1 is performed and the period during which the second DC drive process D2 is performed is continuously changed. If it is changed in stages, the effect of disrupting convection is greater. Therefore, the formation of constant convection in the discharge lamp 90 can be further suppressed, and the unbalanced consumption of electrodes and the unbalanced precipitation of electrode materials can be prevented.

3. The discharge lamp lighting device according to the second embodiment

In the discharge lamp lighting device 10 according to the second embodiment, the control unit 40 changes the length of at least one of the period during which the first AC drive process A1 is executed and the period during which the second AC drive process A2 is performed with time. For example, the control unit 40 may change the length of at least one of the period during which the first AC drive process A1 is executed and the period during which the second AC drive process A2 is performed so as to repeatedly increase and decrease over time. Therefore, a temperature difference (such as tens to hundreds of degrees) can be generated between the two electrodes of the discharge lamp 90, the formation of constant convection in the discharge lamp 90 can be suppressed, the consumption of the electrode imbalance and the precipitation of the electrode material imbalance can be prevented, and the electrode material can be suppressed. Excessive melting of the front end prevents blackening of the electrode material adhering to the inner wall of the seal, and maintains the protrusion of the front end of the electrode well.

In addition, the control unit 40 may change the length of at least one of the period during which the first AC drive process A1 is executed and the period during which the second AC drive process A2 is performed over time so as to repeatedly increase and decrease in stages.

Fig. 9 (A) is a graph showing the time-dependent change of the length of the period during which the DC drive process is performed and the length of the AC drive process, and Fig. 9 (B) is a graph showing the time-dependent change of the frequency and the number of cycles. 9(C) is a graph showing time-dependent changes in the ratio of the anode period. The horizontal axes all represent elapsed time. In addition, from time t15 to time t16 and from time t17 to time t18 are the first intervals, and from time t16 to time t17 are the second intervals.

In Fig. 9(A), the length of the period during which the AC drive process is executed is represented by the solid line E, the length of the period during which the first AC drive process A1 is executed is represented in the first interval, and the second AC drive process A1 is executed in the second interval. The length of the period during which the drive process A2 is performed. In addition, in FIG. 9(A), the length of the period during which the DC drive process is executed is represented by a dotted line F, the length of the period during which the first DC drive process D1 is executed is represented in the first section, and the second section is represented in the second section. The length of the period of the DC drive process D2.

In FIG. 9(B), the number of cycles is represented by a solid line G, the number of cycles for executing the first AC drive process A1 is represented in the first interval, and the number of cycles for executing the second AC drive process A2 is represented in the second interval. In addition, in Fig. 9 (B), represent the frequency with dotted line J, represent the 1st frequency in the 1st AC drive process A1 in the 1st interval, represent the 2nd frequency in the 2nd AC drive process A2 in the 2nd interval. frequency.

In FIG. 9(C), the ratio of the anode period represents the ratio of the time during which the first electrode 92 is an anode in one step period. In addition, when the ratio of the time when the 1st electrode 92 is an anode and the ratio of the time when the 2nd electrode 93 is an anode are totaled, it becomes 1. That is, the relationship between the anode ratio of the first electrode 92 and the anode ratio of the second electrode 93 is expressed by the above formula (1).

In the example shown in FIG. 9(A), one step is set to one second, and the control unit 40 performs control to increase the length of the period during which the first AC drive process A1 is executed in stages from time t15 to time t16. . The control unit 40 performs control to increase the length of the period during which the second AC drive process A2 is executed in steps from time t16 to time t17, after decreasing in steps. The control unit 40 performs control to decrease the length of the period during which the first AC drive process A1 is executed in stages from time t17 to time t18.

In addition, in the example shown in FIG. 9(A), the length of the period during which the first DC drive process D1 and the second DC drive process D2 are executed is constant. Therefore, in order to make the length of one step constant, as shown in FIG. 9(B), the number of cycles is changed according to the length of the period during which the first AC drive process A1 and the second AC drive process A2 are executed. In addition, in the example shown in FIG. 9(B), the first frequency in the first AC drive process A1 and the second frequency in the second AC drive process A2 are all constant values of the same value.

When the driving conditions are changed over time as shown in FIGS. 9(A) and 9(B), the anode ratio of the first electrode 92 changes over time as shown in FIG. 9(C). The larger the anode ratio, the higher the electrode temperature becomes, and the smaller the anode ratio, the lower the electrode temperature becomes. Therefore, FIG. 9(C) means that the temperature of the first electrode 92 changes with time. In addition, the anode ratio of the second electrode 93 is expressed by the formula (1), and changes in the opposite direction to the anode ratio of the first electrode 93 . Therefore, FIG. 9(C) means that the temperature of the second electrode 93 also changes with time.

In addition, in the above-mentioned example, although the example in which the lengths of both the period during which the first AC drive process A1 is executed and the period during which the second AC drive process A2 is performed is changed over time in a manner of repeatedly increasing and decreasing in stages, However, for example, when the thermal conditions of the first electrode 92 and the second electrode 93 of the discharge lamp 90 are greatly different (easiness of raising the temperature of the electrodes, etc.), the period during which the first AC drive process A1 is executed may also be set as follows: And one of the lengths of the period during which the second AC drive process A2 is executed is changed in such a manner that the anode ratio on the one electrode side where the temperature becomes higher is lower than that on the other electrode side.

Like the example shown in FIG. 9(A) to FIG. 9(C), it can be considered that the length of at least one of the period during which the first AC drive process A1 is executed and the period during which the second AC drive process A2 is performed is continuously changed. If it is changed in stages, the effect of disrupting convection is greater. Therefore, the formation of constant convection in the discharge lamp 90 can be further suppressed, and the unbalanced consumption of electrodes and the unbalanced precipitation of electrode materials can be prevented.

4. The discharge lamp lighting device according to the third embodiment

In the discharge lamp lighting device 10 according to the third embodiment, the control unit 40 changes the length of at least one of the period during which the first DC drive process D1 is executed and the period during which the second DC drive process D2 is performed, in time, and causes the period during which the first DC drive process D2 is executed to be executed. The length of at least one of the period of the AC drive process A1 and the period of execution of the second AC drive process A2 changes with time. For example, the control unit 40 may also change the length of at least one of the period during which the first DC drive process D1 is executed and the period during which the second DC drive process D2 is executed in such a manner that it repeatedly increases and decreases over time, so that the first AC drive process is executed. The length of at least one of the period A1 and the period during which the second AC drive process A2 is executed changes with time so as to repeatedly increase and decrease.

Therefore, a temperature difference (such as tens to hundreds of degrees) can be generated between the two electrodes of the discharge lamp 90 , suppressing the formation of constant convection in the discharge lamp 90 , and preventing unbalanced consumption of electrodes and unbalanced deposition of electrode materials.

In addition, the control unit 40 may also change the length of at least one of the period during which the first DC drive process D1 is executed and the period during which the second DC drive process D2 is executed in such a manner that the length of at least one of the period of performing the first DC drive process D1 is repeatedly increased and decreased in stages, so that the length of the period during which the first AC drive process is executed is repeated. The length of at least one of the period of the drive process A1 and the period of execution of the second AC drive process A2 changes with time so as to repeatedly increase and decrease in stages. Therefore, the formation of constant convection in the discharge lamp 90 can be further suppressed, and the unbalanced consumption of electrodes and the unbalanced precipitation of electrode materials can be prevented.

5. The discharge lamp lighting device according to the fourth embodiment

In the discharge lamp lighting device 10 according to the fourth embodiment, the control unit 40 changes the length of at least one of the period during which the first AC drive process A1 is executed and the period during which the second AC drive process A2 is performed, and the length of the first AC drive process A2 is changed with time. The first frequency in the drive process A1 and the second frequency in the second AC drive process A2 vary with time. For example, the control unit 40 may also make the shorter the period of executing the first AC drive process A1, the higher the first frequency is changed, and the shorter the period of executing the second AC drive process A2, the more the second frequency is changed. high.

In general, because the higher the frequency of the driving current I, the arc spot of the molten electrode becomes narrower, so the disappearance of protrusions due to excessive melting can be suppressed, and by alternately applying positive and negative currents in a shorter period, it can be achieved. The electrode tip protrusions melted in the DC driving process are stimulated by particle collisions when the cathode is intermittently supplied during the AC driving process, and the protrusions are maintained satisfactorily. Therefore, it is preferable to control the first frequency and the second frequency relatively high during a period in which the electrode temperature of a certain electrode is increasing (a period in which there is a deviation in the anode ratio).

Therefore, a temperature difference (such as tens to hundreds of degrees) can be generated between the two electrodes of the discharge lamp 90, the formation of constant convection in the discharge lamp 90 can be suppressed, the unbalanced consumption of electrodes and the unbalanced precipitation of electrode materials can be prevented, and the Due to the excessive melting of the electrode tip as the starting point of the arc, the evaporated electrode material adheres to the inner wall of the seal or/and the protrusion disappears, preventing blackening and maintaining the shape of the protrusion at the electrode tip well.

In addition, the control unit 40 may also change the length of at least one of the period during which the first AC drive process A1 is executed and the period during which the second AC drive process A2 is executed in a manner that increases and decreases repeatedly in stages, so that the length of the first AC drive process A1 The first frequency in the process A1 and the second frequency in the second AC drive process A2 change over time so as to repeatedly increase and decrease in stages.

Fig. 10 (A) is a graph showing the time-dependent change of the length of the period during which the DC drive process is performed and the length of the AC drive process, and Fig. 10 (B) is a graph showing the time-dependent change of the frequency and the number of cycles. 10(C) is a graph showing the time-dependent change of the ratio of the anode period. The horizontal axes all represent elapsed time. In addition, from time t19 to time t20 and from time t21 to time t22 are the first intervals, and from time t20 to time t21 are the second intervals.

In Fig. 10(A), the length of the period during which the AC drive process is executed is represented by the solid line K, the length of the period during which the first AC drive process A1 is executed is represented in the first interval, and the second AC drive process A1 is executed in the second interval. The length of the period during which the drive process A2 is performed. In addition, in FIG. 10(A), the length of the period during which the DC drive process is executed is represented by a dotted line L, the length of the period during which the first DC drive process D1 is executed is represented in the first section, and the second section is represented in the second section. The length of the period of the DC drive process D2.

In FIG. 10(B), the number of cycles is represented by a dotted line M, the number of cycles for executing the first AC drive process A1 is represented in the first interval, and the number of cycles for executing the second AC drive process A2 is represented in the second interval. In addition, in FIG. 10(B), the frequency is represented by a solid line N, the first frequency in the first AC drive process A1 is represented in the first interval, and the first frequency in the second AC drive process A2 is represented in the second interval. 2 frequencies.

In FIG. 10(C), the ratio of the anode period indicates the ratio of the time during which the first electrode 92 is an anode in one step period. In addition, when the ratio of time that the first electrode 92 is an anode and the ratio of time that the second electrode 93 is an anode are summed up, it becomes 1. That is, the relationship between the anode ratio of the first electrode 92 and the anode ratio of the second electrode 93 is expressed by the above formula (1).

In the example shown in FIG. 10(A), one step is set to one second, and the control unit 40 performs control to increase the length of the period for executing the first AC drive process A1 in stages from time t19 to time t20. . The control unit 40 performs control to increase the length of the period during which the second AC drive process A2 is executed in steps from time t20 to time t21, after decreasing in steps. The control unit 40 performs control to reduce the length of the period during which the first AC drive process A1 is executed in stages from time t21 to time t22.

In addition, in the example shown in FIG. 10(A), the length of the period during which the first DC drive process D1 and the second DC drive process D2 are executed is constant. Therefore, in order to make the length of one step constant, as shown in FIG. 10(B), the number of cycles is changed according to the length of the period during which the first AC drive process A1 and the second AC drive process A2 are executed. In addition, in the example shown in FIG. 10(B), the frequencies in the first AC drive process A1 and the second AC drive process A2 are such that the shorter the period during which the first AC drive process A1 is executed, the more the first frequency is changed. The higher the value is, the shorter the period for executing the second AC drive process A2 is, and the higher the second frequency is changed.

When the driving conditions are changed over time as shown in FIGS. 10(A) and 10(B), the anode ratio of the first electrode 92 changes over time as shown in FIG. 10(C). The larger the anode ratio, the higher the electrode temperature becomes, and the smaller the anode ratio, the lower the electrode temperature becomes. Therefore, FIG. 10(C) means that the temperature of the first electrode 92 changes with time. In addition, the anode ratio of the second electrode 93 is expressed by the formula (1), and changes in the opposite direction to the anode ratio of the first electrode 93 . Therefore, FIG. 10(C) means that the temperature of the second electrode 93 also changes with time.

Like the example shown in FIG. 10(A) to FIG. 10(C), since the period during which the first AC drive process A1 is executed is shorter, the first frequency is changed higher, and the period during which the second AC drive process A2 is performed is shorter. Shorter, the higher the second frequency changes, so a temperature difference (such as tens to hundreds of degrees) can be generated between the two electrodes of the discharge lamp 90, the formation of constant convection in the discharge lamp 90 can be suppressed, and the consumption of electrode imbalance can be prevented. And the unbalanced precipitation of electrode materials, and inhibit the electrode material after evaporation due to the excessive melting of the electrode front end as the starting point of the arc from adhering to the inner wall of the seal or/and the protrusion disappears, prevent the occurrence of blackening, and maintain the electrode well The shape of the protrusion at the front end.

6. The discharge lamp lighting device according to the fifth embodiment

In the discharge lamp lighting device 10 according to the fifth embodiment, the control unit 40 changes the length of at least one of the period during which the first DC drive process D1 is executed and the period during which the second DC drive process D2 is performed, and the length of the first AC drive process D2 is changed with time. The first frequency in the drive process A1 and the second frequency in the second AC drive process A2 vary with time. For example, the control unit 40 may control the longer the period of executing the first DC drive process D1, the higher the first frequency is changed, and the longer the period of executing the second DC drive process D2, the more the second frequency is changed. higher.

In addition, the control unit 40 may also change the length of at least one of the period during which the first DC drive process D1 is executed and the period during which the second DC drive process D2 is executed over time in a manner that increases and decreases repeatedly in stages, so that the first AC drive The first frequency in the process A1 and the second frequency in the second AC drive process A2 change over time so as to repeatedly increase and decrease in stages.

Therefore, similar to the fourth embodiment, a temperature difference (for example, tens to hundreds of degrees) can be generated between the two electrodes of the discharge lamp 90, the formation of constant convection in the discharge lamp 90 can be suppressed, and the consumption of electrode imbalance and electrode material can be prevented. Unbalanced precipitation suppresses excessive melting of the electrode tip and prevents blackening of the electrode material attached to the inner wall of the seal. In addition, it is possible to suppress the disappearance of the protrusion at the tip of the electrode, which is the starting point of the arc, due to excessive melting, and by alternately applying positive and negative currents in a shorter cycle, the protrusion of the tip of the electrode melted in the DC driving process can be reversed in AC. Stimulation was applied during the driving process, and the shape of the protrusion at the tip of the electrode was maintained well.

7. The circuit configuration of the projector

FIG. 11 is a diagram showing an example of a circuit configuration of a projector according to this embodiment. Projector 500 includes image signal conversion unit 510 , DC power supply unit 520 , discharge lamp lighting unit 10 , discharge lamp 90 , liquid crystal panels 560R, 560G, and 560B, and image processing unit 570 in addition to the optical system described above.

The image signal conversion unit 510 converts the image signal 502 (luminance-color difference signal and/or analog RGB signal, etc.) input from the outside into a digital RGB signal with a predetermined word length, generates image signals 512R, 512G, and 512B, and provides them to image processing device 570.

Image processing device 570 performs image processing on three image signals 512R, 512G, and 512B, and outputs drive signals 572R, 572G, and 572B for driving liquid crystal panels 560R, 560G, and 560B, respectively.

The DC power supply unit 520 converts the AC voltage supplied from the external AC power supply 600 into a constant DC voltage, and supplies it to the image signal conversion unit 510, The image processing device 570 and the discharge lamp lighting device 10 on the primary side of the transformer supply DC voltage.

When the discharge lamp lighting device 10 is started, a high voltage is generated between the electrodes of the discharge lamp 90 to cause dielectric breakdown to form a discharge path, and the drive current I for maintaining the discharge of the discharge lamp 90 thereafter is supplied.

The liquid crystal panels 560R, 560G, and 560B modulate the luminance of the colored lights incident on the respective liquid crystal panels through the optical system described above according to the driving signals 572R, 572G, and 572B, respectively.

CPU (Central Processing Unit) 580 controls the work from turning on the projector to turning it off. For example, a lighting command or a extinguishing command may be output to the discharge lamp lighting device 10 through the communication signal 582 . In addition, the CPU 580 may acquire the lighting information of the discharge lamp 90 from the discharge lamp lighting device 10 through the communication signal 532 .

The projector 500 constructed in this way can further suppress the formation of constant convection in the discharge lamp 90, and prevent the consumption of the electrode imbalance and the precipitation of the electrode material imbalance.

In each of the above-mentioned embodiments, a projector using three liquid crystal panels was exemplified, but the present invention is not limited thereto, and is also applicable to projectors using one, two, or four or more liquid crystal panels.

In each of the above-described embodiments, a transmissive projector was described as an example, but the present invention is not limited thereto, and is also applicable to a reflective projector. Here, the so-called "transmissive type" means that the electro-optic modulation device as a light modulation mechanism such as a transmissive liquid crystal panel is a type that transmits light, and the so-called "reflective type" means that an electro-optic modulation device such as a reflective liquid crystal panel An electro-optic modulation device as a light modulation mechanism such as a micromirror type light modulation device is a reflected light type. As the micromirror type light modulation device, for example, a DMD (Digital Micromirror Device: a trademark of Texas Instruments Inc.) can be used. When the present invention is applied to a reflective projector, the same effect as that of a transmissive projector can be obtained.

The present invention in the case of a front projection type projector for projection from the side from which a projected image is viewed and in a rear projection type projector for projection from the side opposite to the side from which a projected image is viewed ,It will be all right.

In addition, this invention is not limited to the above-mentioned embodiment, Various modifications and implementation are possible within the scope of the gist of this invention.

The present invention includes substantially the same configurations as those described in the embodiments (for example, configurations with the same functions, methods, and results, or configurations with the same purposes and effects). In addition, the present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. In addition, the present invention also includes configurations that produce the same effects as the configurations described in the embodiments, or configurations that can achieve the same purpose. In addition, the present invention also includes configurations in which well-known techniques are added to the configurations described in the embodiments.

For example, in the above-mentioned embodiment, as the following alternating current, an alternating current (rectangular wave alternating current) in which a period in which a predetermined current value of the first polarity is continued and a period in which a predetermined current value of the second polarity is continued is alternately repeated. current) as an example for description, but the alternating current supplied as the driving current I may be an alternating current whose current value changes during the period in which the first polarity or the second polarity lasts, and the above-mentioned alternating current is used as the driving current I to supply.

In addition, for example, the length of the period during which the first DC drive process, the second DC drive process, the first AC drive process, and the second AC drive process are performed, and the number of stages and/or stages for changing the first frequency and the second frequency The time can be set arbitrarily according to the specification of the discharge lamp and the like. In addition, the length of the period during which the first DC drive process, the second DC drive process, the first AC drive process, and the second AC drive process and the first frequency and the second frequency can be continuously changed. In addition, the number of stages and/or the time of stages that change between the first section and the second section may be different.

Claims (10)

1. a lighting apparatus for discharge lamp is characterized by,

Comprise:

The discharge lamp drive division, it supplies with drive current to discharge lamp, drives above-mentioned discharge lamp; With

Control part, it controls above-mentioned discharge lamp drive division;

Above-mentioned control part,

Alternately carry out processing of the 1st DC driven and the 1st AC driving in the 1st interval and handle,

Alternately carrying out processing of the 2nd DC driven and the processing of the 2nd AC driving with the above-mentioned the 1st interval the 2nd different interval,

In above-mentioned the 1st DC driven is handled, to implement to supply with the control that the 1st direct current is used as above-mentioned drive current, the 1st direct current is made of the 1st polar component since the 1st polarity,

In above-mentioned the 1st AC driving is handled, implement to supply with the control that the 1st alternating current is used as above-mentioned drive current, repeat the 1st polar component and the 2nd polar component in the 1st alternating current,

In above-mentioned the 2nd DC driven is handled, to implement to supply with the control that the 2nd direct current is used as above-mentioned drive current, the 2nd direct current is made of the 2nd polar component since the 2nd polarity,

In above-mentioned the 2nd AC driving is handled, implement to supply with the control that the 2nd alternating current is used as above-mentioned drive current, repeat the 1st polar component and the 2nd polar component in the 2nd alternating current,

Make carry out that above-mentioned the 1st DC driven handles during and carry out that above-mentioned the 2nd DC driven handles during at least one side's length change by the time.

2. lighting apparatus for discharge lamp according to claim 1 is characterized by,

Above-mentioned control part make carry out that above-mentioned the 1st DC driven handles during and carry out that above-mentioned the 2nd DC driven handles during at least one side's length change by the time in the mode that increases repeatedly and reduce.

3. lighting apparatus for discharge lamp according to claim 2 is characterized by,

Above-mentioned control part make carry out that above-mentioned the 1st DC driven handles during and carry out that above-mentioned the 2nd DC driven handles during at least one side's length change by the time in the mode that increases repeatedly stage by stage and reduce.

4. lighting apparatus for discharge lamp according to claim 1 and 2 is characterized by,

Above-mentioned control part make carry out that above-mentioned the 1st AC driving handles during and carry out that above-mentioned the 2nd AC driving handles during at least one side's length change by the time.

5. a lighting apparatus for discharge lamp is characterized by,

Comprise:

The discharge lamp drive division, it supplies with drive current to discharge lamp, drives above-mentioned discharge lamp; With

Control part, it controls above-mentioned discharge lamp drive division;

Above-mentioned control part,

Alternately carry out processing of the 1st DC driven and the 1st AC driving in the 1st interval and handle,

Alternately carrying out processing of the 2nd DC driven and the processing of the 2nd AC driving with the above-mentioned the 1st interval the 2nd different interval,

In above-mentioned the 1st DC driven is handled, to implement to supply with the control that the 1st direct current is used as above-mentioned drive current, the 1st direct current is made of the 1st polar component since the 1st polarity,

In above-mentioned the 1st AC driving is handled, implement to supply with the control that the 1st alternating current is used as above-mentioned drive current, repeat the 1st polar component and the 2nd polar component in the 1st alternating current,

In above-mentioned the 2nd DC driven is handled, to implement to supply with the control that the 2nd direct current is used as above-mentioned drive current, the 2nd direct current is made of the 2nd polar component since the 2nd polarity,

In above-mentioned the 2nd AC driving is handled, implement to supply with the control that the 2nd alternating current is used as above-mentioned drive current, repeat the 1st polar component and the 2nd polar component in the 2nd alternating current,

Make carry out that above-mentioned the 1st AC driving handles during and carry out that above-mentioned the 2nd AC driving handles during at least one side's length change by the time.

6. lighting apparatus for discharge lamp according to claim 5 is characterized by,

Above-mentioned control part make carry out that above-mentioned the 1st AC driving handles during and carry out that above-mentioned the 2nd AC driving handles during at least one side's length change by the time in the mode that increases repeatedly and reduce.

7. lighting apparatus for discharge lamp according to claim 6 is characterized by,

Above-mentioned control part make carry out that above-mentioned the 1st AC driving handles during and carry out that above-mentioned the 2nd AC driving handles during at least one side's length change by the time in the mode that increases repeatedly stage by stage and reduce.

8. a projector is characterized by,

Comprise each described lighting apparatus for discharge lamp of claim 1 to 7.

9. the driving method of a discharge lamp, it is characterized as by discharge lamp is supplied with drive current with this discharge tube lighting,

In the 1st interval, alternately carry out the 1st DC driven step and the 1st AC driving step,

With the above-mentioned the 1st interval the 2nd different interval, alternately carry out the 2nd DC driven step and the 2nd AC driving step,

In above-mentioned the 1st DC driven step, supply with the 1st direct current as above-mentioned drive current, the 1st direct current is made of the 1st polar component since the 1st polarity,

In above-mentioned the 1st AC driving step, supply with the 1st alternating current as above-mentioned drive current, repeat the 1st polar component and the 2nd polar component in the 1st alternating current,

In above-mentioned the 2nd DC driven step, supply with the 2nd direct current as above-mentioned drive current, the 2nd direct current is made of the 2nd polar component since the 2nd polarity,

In above-mentioned the 2nd AC driving step, supply with the 2nd alternating current as above-mentioned drive current, repeat the 1st polar component and the 2nd polar component in the 2nd alternating current,

Make carry out above-mentioned the 1st DC driven step during and carry out above-mentioned the 2nd DC driven step during at least one side's length change by the time.

10. the driving method of a discharge lamp, it is characterized as by discharge lamp is supplied with drive current with this discharge tube lighting,

In the 1st interval, alternately carry out the 1st DC driven step and the 1st AC driving step,

With the above-mentioned the 1st interval the 2nd different interval, alternately carry out the 2nd DC driven step and the 2nd AC driving step,

In above-mentioned the 1st DC driven step, supply with the 1st direct current as above-mentioned drive current, the 1st direct current is made of the 1st polar component since the 1st polarity,

In above-mentioned the 1st AC driving step, supply with the 1st alternating current as above-mentioned drive current, repeat the 1st polar component and the 2nd polar component in the 1st alternating current,

In above-mentioned the 2nd DC driven step, supply with the 2nd direct current as above-mentioned drive current, the 2nd direct current is made of the 2nd polar component since the 2nd polarity,

In above-mentioned the 2nd AC driving step, supply with the 2nd alternating current as above-mentioned drive current, repeat the 1st polar component and the 2nd polar component in the 2nd alternating current,

Make carry out above-mentioned the 1st AC driving step during and carry out above-mentioned the 2nd AC driving step during at least one side's length change by the time.

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